1. Field of the Invention
The present invention is related to a technique capable of identifying a source generating an electromagnetic wave.
2. Description of the Related Art
Conventionally, when a magnetic field near either an electronic circuit board or an electronic appliance is measured, the current flows are predicted to be at a position where the strength of this nearby magnetic field is high, and this current is a source of generating a remote electric field.
In a conventional prediction method, the probability exists that such a current will be detected, and that this current is not a source for generating a remote electric field.
For instance, when two current elements (remote electric-field-generating sources) having two phases opposite to each other are present on an object to be measured, an interval xe2x80x9cdxe2x80x9d between these two current elements is longer than a distance xe2x80x9c1xe2x80x9d defined from the object to be measured to a measurement point of the nearby magnetic field. The interval is also sufficiently smaller than a wavelength xe2x80x9cxcexxe2x80x9d thereof. Electric fields generated from both current elements may cancel one another, and thus, these electric fields may not constitute a major factor of a remote electric field. However, in the prediction method of the related art, these currents may be perceived as the source for generating the remote electric field
Similarly, even when currents having opposite phases to each other do not appear, that is, when electric fields radiated to the space have opposite phases to each other in view of the relationship of the intervals of current sources, the currents may be identified as the source generating the remote electric field.
But in the conventional prediction method as used to make the prediction described above, the following problems occur. Since the value of the electric field strength at the remote location is indefinite, the conventional prediction method cannot determine whether this value actually exceeds the controlled value. Even when a measurement is taken of the current flow at the position where the strength of the nearby magnetic field is high, the conventional prediction method cannot determine whether the electric field strength at the remote location is increased, or decreased.
In other words, the conventional prediction method cannot provide a clear definition. That is, in the current distribution over either the electronic circuit board or the electronic appliance, which is the object to be measured, the conventional prediction method cannot clarify what current flowing through which point may constitute the major factor for generating a remote electric field.
Moreover, the conventional prediction method cannot provide a clear definition of how the remote electric field is changed by a variation in the currents flowing at an arbitrary point.
An object of the present invention is to solve these problems, and, accordingly, to provide an electromagnetic-wave-generating-source search method capable of easily determining the source generating a remote electric field, so that the appropriate current/currents may be measured.
To achieve this object, an electromagnetic-wave-generating-source search method, according to an aspect of the present invention, calculates a contributing rate which constitutes a remote electric field of each of the current sources (namely, magnetic-field-generating sources) having an investigation object, and then, the calculated contributing rate is displayed. Specifically, all the remote electric fields caused by all the currents flowing over either an electronic circuit board or an electronic appliance are measured, or calculated. Then, the difference between the remote electric field and an electric field caused by each of the currents is calculated. Thus, another calculation is made of a contributing rate of a current which generates a remote electric field at this point.
In addition, an electronic-wave-generating-source search method according to a further aspect of the present invention is provided. In this embodiment, because the current distribution is multiplied by a coefficient to obtain a remote electric field, it is possible to predict a change in remote electric fields when a current flowing over either the electronic circuit board or the electronic appliance changes.
As a result, this electromagnetic-wave-generating-source search method can clarify whether a current flowing at a certain point constitutes a factor for generating a remote electric field within the current distribution over either the electronic circuit board or the electronic appliance . This electromagnetic-wave-generating-source search method can also clarify how the remote electric field changes in response to changes in the currents flowing at the arbitrary point. Accordingly, this electrornagnetic-wave-generating-source search method can readily identify the electric-field-generating source that should be measured.